Chapter 7

Question 1

System vs Surroundings

Answer 1

System: Uses up energy
Surroundings: Providing energy for function

Question 2

Isothermal

Answer 2

No change in temperature
∆U = 0
Q = W

Question 3

Adiabatic

Answer 3

No heat exchange
Q = 0
∆U = -W

Question 4

Isobaric

Answer 4

No pressure change
Flat line in P-V graph

Question 5

Standard Conditions

Answer 5

• Used in kinetics, equilibrium, and thermodynamic calculations
• 25˚C (298 K)
• 1 atm pressure
• 1 M concentration

Question 6

State Function

Answer 6

Properties of a system at equilibrium
* Independent of path taken to achieve equilibrium
* May be dependent on each other

Examples: pressure (P), density (p), temperature (T), volume (V), enthalpy (H), internal energy (U), Gibbs free energy (G), entropy (S)

Question 7

Process Functions

Answer 7

Define path between equilibrium states
* Include Q (heat) and W (work)

Question 8

Triple Point

Answer 8

Combination of temperature and pressure where all three phases are at equilibrium

Question 9

Critical Point

Answer 9

Temperature and pressure above liquid and gas phases are indistinguishable and heat of vaporization = 0

Question 10

Temperature

Answer 10

Indirect measure of thermal content of a system that looks at average kinetic energy (KE) of particles in a sample

Question 11

Heat

Answer 11

Thermal energy transferred between objects as a result of differences in their temperatures

Question 12

Specific heat (c)

Answer 12

Energy required to raise temperature of 1 g of a substance by 1 ˚C

Question 13

Heat Capacity (mc)

Answer 13

Energy required to raise any given amount of substance 1˚C
* Product of mass and specific heat

Question 14

Constant-Pressure Caolrimeter
(AKA coffee cup calorimeter)

Answer 14

• Exposed to constant (atmospheric) pressure
• As reaction proceeds, temperature of contents measured to determine heat of reaction

Question 15

Constant-Volume Calorimeter
(AKA bomb calorimeter)

Answer 15

• Heats of certain reactions (ex: combustion) can be measured indirectly by assessing temperature change in water bath around reaction vessel

Question 16

Specific Heat of Water

Answer 16

1 cal/g * K
Unit: calories

Question 17

Endothermic Reactions

Answer 17

Increase in heat content of system from surroundings
∆H > 0

Question 18

Exothermic Reactions

Answer 18

Release of heat content from system
∆H < 0

Question 19

Enthalpy of Reaction

Answer 19

Bonds broken - bonds formed

Question 20

Phases of Matter Entropy

Answer 20

Solid < Liquid < Gas

Question 21

Entropy (∆ S)

Answer 21

• Increases as sytem has more disorder/freedom of movement and energy dispersed in spontaneous system
• Entropy of universe can never be decreased spontaneously

Examples:
Freezing (decrease)
Sublimation (increase)
Dissolution (increase)
Fewer moles of gas (decrease)
Heat transferred (increase)
Deposition (largest decrease)

Question 22

Gibbs Free Energy

Answer 22

∆ G = ∆H - T∆ S

Question 23

Equilibrium

Answer 23

∆G = 0

Question 24

Isovolumetric (AKA isochoric)

Answer 24

No change in volume
W = 0
∆U = Q

Question 25

Standard Gibbs Free Energy form Equilibrium Constant

Answer 25

∆G˚rxn = -RTlnKeq

Question 26

Combustion

Answer 26

Reaction of a hydrocarbon with O to produce CO2 and H2O

Question 27

Value of e (from ln)

Answer 27

2.7

Question 28

Gibbs Free Energy from Reaction Quotient

Answer 28

∆Grxn = ∆G˚rxn + RTlnQ = RTlnQ/Keq

Question 29

Spontaneous Reaction

Answer 29

∆G < 0 If forward: Keq > Q If backward: Keq < Q

Question 30

Heat transfer no phase change

Answer 30

q = mc∆T

Question 31

Heat transfer during phase change

Answer 31

q = mL **temperature is constant during phase change**

Question 32

Entropy Change

Answer 32

∆S = Qrev/T | Q rev = heat input